CHICAGO — Two mothers who lost sons to gun violence joined ministers and an activist group Tuesday in an unusual lawsuit against three Chicago suburbs, alleging that weak oversight of gun stores has allowed criminals to easily obtain weapons flowing into a metropolitan area besieged by gang violence.

The lawsuit accuses the communities of Lyons, Riverdale and Lincolnwood of violating the civil rights of residents in Chicago's largely African American neighborhoods by failing to take steps to make sure gun stores are not selling to people who should not be allowed to carry them.

"Those illegal firearms are flowing into a pocket of communities violating the civil rights of the individuals who reside there, who are afraid to go near their windows or let their children play in the park, much less their own yards," said Kathleen Sances, a member of the Coalition for Safe Chicago Communities, one of the plaintiffs in the lawsuit.

Five individuals — including two ministers and two mothers whose children were the victims of gun violence — joined the lawsuit that demands that the communities improve the oversight of the businesses and implement security measures the stores must implement.

Seven people were shot to death in Chicago during the three-day Fourth of July weekend, including 7-year-old Amari Brown, focusing national attention on the city's gun violence and statistics showing the number of homicides and shootings has again climbed.

One of the plaintiffs is Annette Nance-Holt, whose son Blair was killed in 2007 shielding a friend on a city bus after a gang member boarded and opened fire on a rival group.

"Our communities are being flooded with guns," she said. "We have to do something... to take a stand to help get these guns off the street."

Attorney Michael Persoon said he knows of no other similar lawsuit in Illinois and does not know of anywhere else in the country where a lawsuit has been filed alleging that municipalities violated someone's civil rights by failing to adequately oversee the actions of local businesses.

A gun rights advocate agreed, though he called the lawsuit as a twist on a longstanding attack on gun owners.

"It's is just another harassment lawsuit," said Richard Pearson, the executive director of Illinois State Rifle Association. "They found the gun shops did nothing wrong so they are trying to put pressure on the communities to do something that will drive (the stores) out of business.

Though the city of Chicago is not a party in the lawsuit, Lyons Village President Christopher Getty said in a statement released by a public relations firm characterized the lawsuit as an effort by Chicago to "pass the blame onto outside communities and businesses for the crimes and short-comings in dealing with crimes" in the city. An official with Lincolnwood declined comment, and a call to Riverdale was not returned.

Though they sued the communities and not the stores themselves, members of the group pointed to a Chicago Police Department study that showed that between 2009 and 2013, 2,000 guns sold in the stores in Riverdale and Lyons were used in crimes.

But, they said that they can dramatically reduce the flow of illegal guns into their communities if the three suburbs are required to do such things as install surveillance cameras and train employees on how to stop straw purchasers who buy legally guns and provide them to criminals.